This invention relates to a counter for counting repetitive phenomena, such as the number of pages printed by a page printer.
Electrophotographic page printers and copiers are equipped with counters that count the cumulative number of pages or copies printed to determine replacement times for supplies and components such as toner and photosensitive drums, or to indicate when the printer or copier is at the end of its service life. Examples of counters employed in the prior art include mechanical counters, electronic counters using a battery-backed-up memory to store the count value, and electronic counters using a floppy disk to store the count value. These prior-art counters are expensive, and are inconveniently large.
Counts can more conveniently be kept in an electrically erasable and programmable read-only memory (EEPROM), which does not require battery back-up. Current EEPROMs, however, can be rewritten only about ten to twenty thousand times, which is far less than the number of pages printed by a page printer or copier during its service life. For this reason, EEPROM-based counters have not been used.